1. Field of the Invention
The present invention relates to a printing apparatus equipped with an inking unit for supplying ink to a printing plate mounted on a plate cylinder through an inking cylinder or roller. More particularly, the present invention relates to one type of printing apparatus such as a satellite type rotary press whose inking unit is arranged above the plate cylindar.
2. Description of the Prior Art
A conventional satellite type rotary press such as a satellite type offset rotary press has been broadly known as disclosed in "News Paper Print, Printing Edition Reversed Version" published by Japan News Paper Association (Corporation) on Oct. 31, 1980, pp. 276, right column, lines 14 to 17. Such a rotary press comprises one common impression cylinder, and four sets of plate cylinders and blanket cylinders arranged around the impression cylinder to perform a four-colors printing on a single side of paper. In such a rotary press, a paper web travels through the four plates according to feeding work of the impression cylinder without a long pass for the paper web among the plate cylinders. Thus, such a rotary press provides an advantage in estimate accuracy owing to the paper web being stable on the impression cylinder. On the other hand, each of the plate cylinders is equipped with an inking unit including a plularity of rollers as shown in Japanese Patent Laid-Open Publication No. 63-28650 entitled "Printing Apparatus", in FIG. 5 on page 5.
Another type of satellite offset rotary press has been recently provided as shown in "Print Magazine the March issue" published by Print Society Inc., Printing Department, on Mar. 15, 1988, page 67 line 26 in center column to line 25 in right column including drawings. This type can reduce the number of rollers by using an ink metering cylinder (mesh roller).
One typical apparatus is shown in FIG. 2 wherein four inking units I1, I2, I3 and I4 are respectively associated with plate cylinders P1, P2, P3 and P4. The inking units I1, I2, I3 and I4 are essentially the same in construction, so that only one unit I1 will be explained. The inking unit I1 includes a fountain roller 2 which is partially dipped in ink stored in a fountain pan 1'(1). At the downstream side of the fountain roller 2, a mesh roller 3, functioning as an ink metering roller, is set so as to be in contact with the foutain roller 2. The mesh roller 3 is also in contact with a first doctor blade 6 for metering the ink on the circumferential surface of the mesh roller 3. Further, the downstream side of the mesh roller 3 is in contact with a pair of form rollers 4 and 5 which are in contact with a printing plate set on the circumferential surface of the plate cylinder P1. The mesh roller 3 is furthermore in contact with an elastic surface roller 7 at the downstream side of the form rollers 4 and 5 in the revolving direction of the mesh roller 3. The elastic surface roller 7 is in contact with a hard surface roller 8 whose circumferential surface is also in contact with a second doctor blade 9 for removing an excess ink. The elastic surface roller 7, the hard surface roller 8 and the second doctor blade 9 constitute an excess ink removing means 10.
As shown in FIG. 2, this apparatus further comprises a plurality of ink pans 11, 12 and 13 for receiving the ink scraped by the doctor blades 6 and 9 and/or the ink dropped from the fountain pan 1 and 1'. The inking units I1, I2, I3 and I4 and the plate cylinders P1, P2, P3 and P4 are respectively revolved in respective directions shown in FIG. 2 in accordance with revolving direction of a common impression cylinder IC around which a paper web WP is travelling. Further in FIG. 2, the reference numerals B1, B2, B3 and B4 denote blanket cylinders correspondingly arranged in contact with the plate cylinders P1, P2, P3 and P4, respectively. The reference numerals D1, D2, D3 and D4 denote dampening means arranged in the respective plate cylinders, and the reference GR denotes a guide roller for guiding the paper web.
However, the above described satellite type offset rotary press has also provided some demerits owing to the roller arrangement of the inking unit. Every inking unit employing the ink metering roller (mesh roller) 3 has the same arrangement of rollers, so that the first doctor blades 6 of the first plate cylinder P1 and the fourth plate cylinder P4 should be set in remarkably narrow space defined between the fountain pan 1' and the ink pan 12. This narrow space has caused difficulty or limitations for the operation and/or maintenance of the doctor blade 6. The doctor blade 6 should be adjusted to suitably fit its contact angle with the mesh roller 3 by manually adjustment, and thus this apparatus has required an experienced operator and relatively complicated operations and long periods for its adjustment and/or repairment. This demerit will reduce working efficiency of whole printing process.